Well I wont mention anything anyone else has, because thats not fun. I would have to say tey are all pretty bad, and as for the Think one, I think (wtf) that we should be able to thinkand not have consequences. Like, being able to say, Omg, 6 x 7 equals 42, but on the other hand being able to know Quantam Physics, Programming, Nuclear Physics, thats too much. We should only be able to think enough so that we are an intelligent species.
Ok, my turn for Worst Thing Ever. It would probably be eating red meat. If we never ate red mate we would not evolve into the extremely intelligent species we are, and therefore not fuck up the planet. However, we were too stupid to know this when we ate red meat at the time, so it was inevitable. And even worse, it is impossible to live a long and fruitful life without eating red meat. So we will continue to evolve and get smarter and smarter, but by the time we are supersmart we will all be dead because of some random thing we did. Maybe too many users on the Interent or something. Massive nuke. I dont know.
Maybe even just existence. But we cant do anything about it now, we should be looking to how to fix those problems we have created. Call me a hypocrite, but we should be fixing these problems instead of whinging about them.
My Two Cents.
Note: 9/11 was pretty bad too.